A New Safety Approach in the Design of Fast Reactors

A new approach to achieving fast reactor safety goals is becoming apparent in the U.S. Fast Reactor Program. Whereas the “defense-in-depth” philosophy still prevails, there has been a tangible shift toward emphasizing passive mechanisms to protect the reactor and provide public safety rather than relying on addon active, engineered safety systems. Intrinsic reactivity feedback mechanisms, based on fundamental nuclear cross section and material motion changes with temperatures, combined with passive methods to assure removal of decay heat, are being quantified and included in analysis techniques to demonstrate the exceptional robustness of current advanced liquid-metal-cooled reactor designs in the United States.